This invention relates to thermoplastic resin compositions, more particularly to polyarylate compositions, a method to synthesize the composition and articles made from this and related compositions.
Optical films are well known in the art. Glass has been widely used for several optical applications, due to its excellent characteristics, such as transparency, a high transmittance in the visible light range and temperature resistance. Nevertheless, the use of glass as a sub layer or support in optical applications has limitations in its application, especially in the area of flexible optical devices, due to its high weight and brittleness. In addition, the brittleness of glass, limits its use in continuous processing leading to a very low final productivity.
It is desirable to replace glass in numerous applications with transparent polymeric films, such as polyesters (e.g., polyethyleneterephthalate), polyacrylates (e.g., polymethylmethacrylate) or polycarbonate. Although these polymers have good properties, they possess poor transmittance, limited heat resistance and a low glass transition temperature (Tg), that would limit employment of these polymers in optical applications.
U.S. Pat. Nos. 3,546,165; 4,387,209; 4,401,803 describe fluorene based polyesters with isophthalic or terephthalic acids which are thermally stable but have unsatisfactory mechanical properties and low inherent viscosity. While U.S. Pat. No. 4,533,511 discloses a process for spinning fibers obtained from the polycondensation product of 9,9-bis-(4-hydroxyphenyl)-fluorene and a mixture of isophthalic acid chloride and terephthalic acid chloride.
The U.S. Pat. No. 4,967,306 discloses a fluorene diol with isophthalic and terephthalic acid polyester containing a very low level of oligomeric material but having a tensile strength, elongation, chemical resistance, temperature stability, ultraviolet resistance and vacuum stability higher than the copolymers containing oligomeric species. However, the films containing small amounts of oligomer “yellow” or degrade upon limited exposure to ultraviolet radiation.
Polyarylates composed of fluorene diol and isophthalic acid as reported in Journal of Applied Polymer Science, Vol. 29, p. 35 to 43 (1984) was found to possess insufficient abrasion resistance and film coating quality was poor. Polyarylates derived from phenolphthalein and its derivatives exhibit combination of properties of high softening temperature, good solubility, high thermal resistance and considerable mechanical strength at higher temperatures. (B. D. Priddy, Jr.; J. E. McGrath, Polym Preprints 33(2), 231 (1992); S. S. Vibhuthe et al J. Polym. Sci. Polym. Chem. 35, 3227 (1997). The various classes of polymers such as polyesters derived from bis(hydroxyphenyl)fluorene, cyclic olefins and poly(aryl ether sulfone)s have been considered for display applications under various trade names by Promerus, Ferrania, and Sumitomo Bakelite Companies. These polymers show Tg from 223 to 330° C.
The polymer film should show excellent optical properties in addition to good thermal properties to allow high temperature processing, good mechanicals and also excellent barrier properties in order to find its use in optical applications. There is a continuing need for polymeric thermoplastic compositions to possess a good balance of transparency and processability, in addition to good mechanical and thermal properties.